This invention relates to a magnetic head for performing recording and reproduction of information while moving relatively with respect to a magnetic medium such as a magnetic disk, and a lapping method thereof, and a magnetic disk drive unit using the magnetic head.
In recent years, in a magnetic disk drive unit, recording density has been rapidly improved. Accordingly, it has been demanded that an air bearing height of the magnetic head with respect to the magnetic recording medium should be decreased to the utmost.
As shown in FIG. 7, the magnetic disk drive unit is completed by combining magnetic heads 70, each of which is fixed to a support spring 74, with magnetic disks 73, which are recording medium. Magnetically recorded information is written and read by means of the magnetic head 70 that moves over the rotating magnetic disks 73 by means of a drive unit 75.
In order to create an air bearing surface of magnetic head for realizing such a small air bearing height, lapping operation is generally performed. The lapping operation is usually performed on a soft metallic surface plate. Specifically, as shown in FIG. 8, a head (not shown) bonded to a lapping jig is pressedly slid while a lapping fluid (slurry 80) mainly containing hard abrasives such as diamond is dripped onto a rotating soft metallic lapping surface plate 8 via a slurry supply tube 81, by which lapping operation is performed by abrasives embedded in the lapping plate 8 or rolling abrasives rolling between the lapping plate and the head. A conditioning ring 9 is used to maintain the flatness of the soft metallic lapping plate 8 during the lapping operation.
In the magnetic head using a magneto-resistive (MR) or giant-magneto-resistive (GMR) head to read a signal, it is necessary to precisely machine the element height of an MR or GMR element that is important for reproduction characteristics. At present, a method described in JP-A-2-95572 specification is used to control this element height. Specifically, in this method, the lapping amount during lapping operation is always monitored by using a lapping amount detecting element, and the monitored result is fed back to a lapping apparatus, by which lapping is performed while the bend and inclination of the alignment of the elements in a row bar is controlled.